Autism Spectrum Disorders

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The autism spectrum disorders, or ASDs, are a group of neurological conditions associated with an decreased ability to communicate and relate to others, and repetitive behaviors, such as obsessively arranging objects or following very specific routines. The conditions in this group can range from mild to severe. Diagnosis is usually made in early childhood, but each condition can present later in life as well.

An 18-month old boy with autism, obsessively stacking cans. Source: Wikimedia Commons


Contents

Other Names

Types

There are five separate conditions included in the group of autism spectrum disorders: autism, Asperger syndrome, childhood disintegrative disorder, Rett syndrome, and pervasive developmental disorder.

Autistic disorder (classic autism)

Classic autism is the best-known and most common of the autism spectrum disorders, affecting one in 150 births in the United States. [1] Individuals with autism have difficulties with social interaction, verbal and nonverbal communication, and exhibit repetitive behaviors or narrow, obsessive interests. These behaviors can range in impact from mild to disabling. Autism varies widely in its severity and symptoms and may go unrecognized.

Asperger syndrome

Asperger syndrome, first described in the 1940s, was only added to the DSM-IV in 1994 and is gradually becoming a more commonly diagnosed condition. People with Asperger syndrome retain their early language skills and often have an extensive vocabulary. They frequently have a favorite topic that they can talk about at length. They may have extensive rituals, have difficulty with social interactions and be physically clumsy.

Childhood disintegrative disorder

Childhood disintegrative disorder, much less common than autism, is characterized by normal development in the first several years of life, followed by a significant loss of social, language, and physical skills. Mental retardation may also occur.

Very few children who have an autism spectrum disorder (ASD) diagnosis meet the criteria for childhood disintegrative disorder (CDD). Fewer than two children per 100,000 with ASD can be classified as having CDD. CDD has a strong male preponderance.[2] Symptoms may appear by age 2, but the average age of onset is between 3 and 4 years. Until this time, the child has age-appropriate skills in communication and social relationships. The long period of normal development before regression helps differentiate CDD from Rett syndrome.

The loss of such skills as vocabulary are more dramatic in CDD than they are in classical autism. The diagnosis requires extensive and pronounced losses involving motor, language, and social skills.[3] CDD can also be accompanied by loss of bowel and bladder control, seizures, and a very low IQ.

Rett syndrome

Rett syndrome is an X-linked dominant disorder mainly caused by a mutation in the MECP2gene. This condition primarily affects girls (affected boys die shortly after birth) and is characterized by normal development until about the sixth to eighteenth month of life. Skills then begin to slow and eventually regress, especially language skills and the use of the hands. Most girls affected with Rett syndrome require a great deal of assistance with activities of daily living. Physical, occupational, and speech therapy can help with problems of coordination, movement, and speech.

Pervasive developmental disorder - not otherwise specified (PDD-NOS)

This condition is diagnosed when features of the autism spectrum disorders are noted but the person does not meet diagnostic criteria for the other specific disorders. It is a diagnosis of exclusion. This condition can be thought of as atypical autism as it may present with a later age at onset, atypical or milder symptoms than classic autism.

Symptoms

Symptoms vary according to the disorder, but some symptoms are common to all the disorders:

  • Difficulties with social interaction
  • Problems with verbal and nonverbal communication
  • Repetitive behaviors or narrow, obsessive interests

These behaviors can range in their effects from mild to disabling.

Social difficulties

The hallmark of autism is impaired social interaction. Parents are usually the first to notice symptoms of autism in their child. As early as infancy, a baby with autism may be unresponsive to people or focus intently on one item to the exclusion of others for long periods of time. A child with autism may also appear to develop normally and then withdraw and become indifferent to social engagement.

Children with autism may fail to respond to their name and often avoid eye contact with other people. They have difficulty interpreting what others are thinking or feeling because they can’t understand social cues, such as tone of voice or facial expressions, and don’t watch other people’s faces for clues about appropriate behavior. They may lack empathy (the capacity to recognize or understand the emotions of others).

It is also common for people with ASD to have difficulty regulating their emotions. This can take the form of immature behavior such as crying in class or inappropriate verbal outbursts. The individual with ASD might also be disruptive and physically aggressive at times, making social relationships difficult. They have a tendency to lose control, particularly when they're in a strange or overwhelming environment, or when angry and frustrated. They may at times break things, attack others, or hurt themselves. In frustration, some bang their heads, pull their hair, or bite their arms

Many children with autism have a reduced sensitivity to pain, but are abnormally sensitive to sound, touch, or other sensory stimulation. These unusual reactions may contribute to behavioral symptoms such as a resistance to being cuddled or hugged.

While people with schizophrenia may show some autistic-like behavior, their symptoms usually do not appear until the late teens or early adulthood. Most people with schizophrenia also have hallucinations and delusions, which are not found in autism.

Communication difficulties

By age three, most children have passed predictable milestones on the path to learning language. One of the earliest is babbling. By his first birthday, a typical toddler says words, turns when he hears his name, points when he wants a toy, and when offered something distasteful, makes it clear that the answer is “no.”

Some children diagnosed with ASD remain mute throughout their lives. Some infants who later show signs of ASD coo and babble during the first few months of life, but they soon stop. Others may be delayed, developing language as late as age five to nine. Some children may learn to use communication systems such as pictures or sign language.

Those who do speak often use language in unusual ways. They seem unable to combine words into meaningful sentences. Some speak only single words, while others repeat the same phrase over and over. Some ASD children parrot what they hear, a condition called echolalia. Although many children without ASD go through a stage where they repeat what they hear, it normally passes by three years of age.

Some children only mildly affected with ASD may exhibit slight delays in language, or even seem to have precocious language and unusually large vocabularies, but have great difficulty in sustaining a conversation. While it can sometimes be difficult to understand what ASD children are saying, their body language may also be challenging to read. Facial expressions, movements, and gestures rarely match what they are saying. Also, their tone of voice fails to reflect their feelings. A high-pitched, sing-song, or flat, robot-like voice is common. Some children with relatively good language skills speak like little adults, failing to pick up on the “kid-speak” that is common in their peers. As people with ASD grow up, they can become increasingly aware of their difficulties in understanding others and in being understood. As a result they may become anxious or depressed.

Repetitive behaviors

Although children with ASD usually appear physically normal and have good muscle control, odd repetitive motions may set them off from other children. These behaviors might be extreme and highly apparent or more subtle. Some children and older individuals spend a lot of time repeatedly flapping their arms or walking on their toes. Some suddenly freeze in position.

ASD children need, and demand, absolute consistency in their environment. A slight change in any routine—mealtime, dressing, taking a bath, going to school at a certain time and by the same route—can be extremely disturbing.

Repetitive behavior sometimes takes the form of a persistent, intense preoccupation. For example, the child might be obsessed with learning all about vacuum cleaners, train schedules, or lighthouses. Often there is great interest in numbers, symbols, or science topics. Such intense interests are common in Asperger syndrome.

Causes

The autism spectrum disorders have no single, known cause. Given the complexity of the disease, the range of autistic disorders and the fact that no two children with autism are alike, it's probable that there are many causes. These may include:

  • Genetic: There appears to be a number of genes involved in autism. Some may increase the likelihood of developing the disorder; others affect the development of the brain or the way the brain communicates. Some genetic errors seem to be inherited, whereas others occur spontaneously during development.
  • Environmental factors: It is likely that environmental factors, such as viral infections and toxins, play a role in the development of ASD. As with many conditions, genetic and environmental factors may co-exist.
  • Other causes: Other factors may include difficulties during labor and delivery and disorders of the immune system. Some researchers believe that damage to the amygdala—a portion of the brain that serves as a danger detector—may play a role in autism.

Diagnosis

The ASDs are diagnosed by an experienced clinician who observes the child and learns about his patterns of behavior, then compares those behaviors to a set of criteria that are listed in the main reference manual for psychiatry, the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition;Text Revision) (DSM-IV-TR).[4] [5]

At present, except for in Rett syndrome, there is no simple test like a blood test that reveals whether a child has an ASD. However, promising results are emerging in the field of autism with tests that track what a child is looking at, and in the future such a test may become standard for autism at least.[6][7]

Screening

A well child check-up should include a developmental screening test. If a child's pediatrician does not routinely check the child with such a test, parents should ask for it to be done. Parents' own observations and concerns about their child's development are essential in helping to screen the child. Reviewing family videotapes, photos, and baby albums can help parents remember when each behavior was first noticed and when the child reached certain developmental milestones.

Several "screening instruments," which are basically checklists, have been developed to quickly gather information about a child's social and communicative development within medical settings. Among them are the Checklist of Autism in Toddlers (CHAT)[8], the modified Checklist for Autism in Toddlers (M-CHAT)[9], and the Social Communication Questionnaire (SCQ) (for children 4 years of age and older). [10]

Some screening instruments rely solely on parents' responses to a questionnaire, and some rely on a combination of parents' reports and the doctor's observations. Screening instruments don't provide diagnoses, but they help clinicians decide whether a child needs to be referred to an expert for possible diagnosis of ASD.

The above screening methods may not identify children with mild ASD, such as those with high-functioning autism or Asperger syndrome. The Autism Spectrum Screening Questionnaire (ASSQ) and the most recent, the Childhood Asperger Syndrome Test (CAST), are more helpful in finding school-age children with Asperger syndrome or higher functioning autism. These tools concentrate on social and behavioral impairments in children without significant language delay.

If, following the screening process or during a routine well child check-up, a child's doctor sees any of the possible indicators of ASD, further evaluation by a specialist is needed.

Comprehensive diagnostic evaluation

The second stage of diagnosis must be comprehensive in order to accurately rule in or rule out an ASD or other developmental problem. This evaluation may be done by a multidisciplinary team that includes a psychologist, a neurologist, a psychiatrist, a speech therapist, or other professionals who diagnose children with ASD.

Because ASDs are complex disorders and may involve other neurological or genetic problems, a comprehensive evaluation should include neurologic tests and genetic tests, along with in-depth cognitive and language testing. In addition, measures developed specifically for diagnosing autism are often used. These include the Autism Diagnosis Interview-Revised (ADI-R)[11] and the Autism Diagnostic Observation Schedule (ADOS-G).[12] The ADI-R is a structured interview that contains over 100 items and is conducted with a caregiver. It consists of four main factors—the child's communication, social interaction, repetitive behaviors, and age-of-onset of symptoms. The ADOS-G is an observational measure used to look for socio-communicative behaviors that are often delayed, abnormal, or absent in children with ASD.

Still another instrument often used by professionals is the Childhood Autism Rating Scale (CARS).[13] It aids in evaluating the child's body movements, adaptation to change, listening response, verbal communication, and relationship to people. It is suitable for use with children over 2 years of age. The examiner observes the child and also obtains relevant information from the parents. The child's behavior is rated on a scale based on deviation from the typical behavior of children of the same age.

Two other tests that are used to assess any child with a developmental delay are a formal audiologic hearing evaluation and a lead screening. Lead screening is essential for children who remain for a long period of time in the oral-motor stage in which they put any and everything into their mouths. Children with an autistic disorder may have elevated blood lead levels if they live in old houses that may have been painted with lead-based paint.

Customarily, an expert diagnostic team has the responsibility of thoroughly testing, evaluating the child, assessing the child's unique strengths and weaknesses, and determining a formal diagnosis. The team will then meet with the parents to explain the results of the evaluation.

Genetic Testing

The variability of the ASDs likely reflects the interaction of multiple genes and the existence of distinct genes and gene combinations among those affected. Children with dysmorphic features, congenital anomalies, mental retardation, or family members with developmental disorders are those most likely to benefit from extensive medical testing and genetic consultation. The yield of genetic testing is much less in high-functioning children with a normal appearance and IQ and moderate social and language impairments. Genetic counseling justifies testing, but until autism genes are identified and their functions are understood, prenatal diagnosis will exist only for the rare cases ascribable to single-gene defects or overt chromosomal abnormalities. Parents who wish to have more children must be told of their increased statistical risk.

Treatment

Therapies

Among the many methods available for treatment and education of people with autism, applied behavior analysis (ABA) has become widely accepted as an effective treatment. The goal of behavioral management is to reinforce desirable behaviors and reduce undesirable ones. [14]. However, there is increasing evidence for other interventions that give parents more choice. These include the Early Denver Model[15], the DIR/Floortime Model and the PLAY Project[16].

An effective behavioral treatment program will build on the child's interests, offer a predictable schedule, teach tasks as a series of simple steps, actively engage the child's attention in highly structured activities, and provide regular reinforcement of behavior. Parental involvement has emerged as a major factor in treatment success. Parents work with teachers and therapists to identify the behaviors to be changed and the skills to be taught. Recognizing that parents are the child's earliest teachers, more programs are beginning to train parents to continue the therapy at home.

Children older than three years of age usually have school-based, individualized, special education. The child may be in a segregated class with other autistic children or in an integrated class with children without disabilities for at least part of the day. In these programs, teachers often involve the parents, giving useful advice in how to help their child use the skills or behaviors learned at school when they are at home.[17]

In elementary school, the child should receive help in any skill area that is delayed and, at the same time, be encouraged to grow in his or her areas of strength. Ideally, the curriculum should be adapted to the individual child's needs. Many schools today have an inclusion program in which the child is in a regular classroom for most of the day, with special instruction for a part of the day. This instruction should include such skills as learning how to act in social situations and in making friends. Although higher-functioning children may be able to handle academic work, they too need help to organize tasks and avoid distractions.

During middle and high school years, instruction will begin to address such practical matters as work, community living, and recreational activities. This should include work experience, using public transportation, and learning skills that will be important in community living.

Holistic and alternative treatments

In an effort to do everything possible to help their children, many parents seek new treatments. Some treatments are developed by reputable therapists or by parents of a child with ASD. Although an unproven treatment may help one child, it may not prove beneficial to another. To be accepted as a proven treatment, the treatment should undergo clinical trials, preferably randomized, double-blind trials, that allow for a comparison between treatment and no treatment. Following are some of the interventions that have been reported to have been helpful to some children but whose efficacy or safety has not been proven.

Dietary interventions are based on the idea that food allergies cause symptoms of autism, and that an insufficiency of a specific vitamin or mineral may cause some autistic symptoms. A diet that some parents have found to be helpful for their autistic child is a gluten-free, casein-free diet. Gluten is a substance that is found in the seeds of various cereal plants—wheat, oat, rye, and barley. Casein is the principal protein in milk. Since gluten and milk are found in many of the foods we eat, following a gluten-free, casein-free diet is difficult.

A supplement that some parents feel is beneficial for an autistic child is Vitamin B6, taken with magnesium (which makes the vitamin effective). The results of research studies are mixed. Some children respond positively, some negatively, some not at all or very little.

In the search for treatments for autism, there has been discussion in the last few years about the use of secretin, a substance approved by the Food and Drug Administration (FDA) for a single dose normally given to aid in diagnosis of a gastrointestinal problem. Anecdotal reports have shown improvement in autism symptoms, including sleep patterns, eye contact, language skills, and alertness. Several clinical trials conducted in the last few years have found no significant improvements in symptoms between patients who received secretin and those who received a placebo. [18] [19]

Medications

Medications are often used to treat behavioral problems, such as aggression, self-injurious behavior, and severe tantrums, that keep the person with ASD from functioning more effectively at home or school. The medications used are those that have been developed to treat similar symptoms in other disorders. Many of these medications are prescribed “off-label”. This means they have not been officially approved by the FDA for use in children, but the doctor prescribes the medications if he or she feels they are appropriate for a child. Further research needs to be done to ensure not only the efficacy but the safety of some psychotropic agents used in the treatment of children and adolescents. Commonly used medications are:

  • The Selective Serotonin Reuptake Inhibitors (SSRI's) are the medications most often prescribed for symptoms of anxiety, depression, and/or obsessive-compulsive disorder (OCD). Only one of the SSRI's, fluoxetine, (Prozac) has been approved by the FDA for both OCD and depression in children age 7 and older. Three that have been approved for OCD are fluvoxamine (Luvox), sertraline (Zoloft), and clomipramine (Anafranil). Treatment with these medications can be associated with decreased frequency of repetitive, ritualistic behavior and improvements in eye contact and social contacts.
  • Antipsychotic medications have been used to treat severe behavioral problems. These medications work by reducing the activity in the brain of the neurotransmitter dopamine. Commonly used antipsychotics include haloperidol (Haldol), thioridazine, fluphenazine, and chlorpromazine. Haloperidol was found in more than one study to be more effective than a placebo in treating serious behavioral problems.[20] However, haloperidol, while helpful for reducing symptoms of aggression, can also have adverse side effects, such as sedation, muscle stiffness, and abnormal movements.
  • Risperidone (Risperdal) has recently been approved by the FDA for the symptomatic treatment of irritability in autistic children and adolescents ages 5 to 16. The approval is the first for the use of a drug to treat behaviors associated with autism in children. These behaviors are included under the general heading of irritability, and include aggression, deliberate self-injury and temper tantrums.
  • Olanzapine (Zyprexa) and other antipsychotic medications are used “off-label” for the treatment of aggression and other serious behavioral disturbances in children, including children with autism.
  • Seizures are found in one in four persons with ASD, most often in those who have low IQ or are mute. [21] They are treated with one or more of the anticonvulsants. These include such medications as carbamazepine (Tegretol), lamotrigine (Lamictal), topiramate (Topamax), and valproic acid (Depakote). The level of the medication in the blood should be monitored carefully and adjusted so that the least amount possible is used to be effective. Although medication usually reduces the number of seizures, it cannot always eliminate them.
  • Stimulant medications such as methylphenidate (Ritalin), used safely and effectively in persons with attention deficit hyperactivity disorder, have also been prescribed for children with autism. These medications may decrease impulsivity and hyperactivity in some children, especially higher functioning children.
  • Several other medications have been used to treat ASD symptoms; among them are other antidepressants, naltrexone, lithium, and some of the benzodiazepines such as diazepam (Valium) and lorazepam (Ativan). The safety and efficacy of these medications in children with autism has not been proven. Since people may respond differently to different medications, a child's unique history and behavior will help the doctor decide which medication might be most beneficial.

Living with Autism Spectrum Disorder

Childhood

When a child has been evaluated and diagnosed with an autism spectrum disorder, parents will usually begin to look at treatment options and at the types of aid available for a child with a disability. Parents often find that learning as much possible about the disorder helps them become effective advocates.

For every child eligible for special programs, each state guarantees special education and related services. The Individuals with Disabilities Education Act (IDEA) is a Federally mandated program that assures a free and appropriate public education for children with diagnosed learning deficits. Usually children are placed in public schools and the school district pays for all necessary services. These will include, as needed, services by a speech therapist, occupational therapist, school psychologist, social worker, school nurse, or aide.

By law, the public schools must prepare and carry out a set of instruction goals, or specific skills, for every child in a special education program. The list of skills is known as the child's Individualized Education Program (IEP). The IEP is an agreement between the school and the family on the child's goals. When a child's IEP is developed, parents will be asked to attend the meeting. There will be several people at this meeting, including a special education teacher, a representative of the public schools who is knowledgeable about the program, other individuals invited by the school or by the parents (often a relative, a child care provider, or a supportive close friend who knows the child well). Parents play an important part in creating the program, as they know their child and his or her needs best. Once a child's IEP is developed, a meeting is scheduled once a year to review the child's progress and to make any alterations to reflect his or her changing needs.

If a child is under 3 years of age and has special needs, he or she should be eligible for an early intervention program. This program is available in every state. Each state decides which agency will be the lead agency in the early intervention program. The early intervention services are provided by workers qualified to care for toddlers with disabilities and are usually in the child's home or a place familiar to the child. The services provided are written into an Individualized Family Service Plan (IFSP) that is reviewed at least once every 6 months. The plan will describe services that will be provided to the child, but will also describe services for parents to help them in daily activities with their child and for siblings to help them adjust to having a brother or sister with ASD.

The adolescent years

Adolescence is a time of stress and confusion; and it is no less so for teenagers with autism. Like all children, they need help in dealing with their budding sexuality. While some behaviors improve during the teenage years, some get worse. Increased autistic or aggressive behavior may be one way some teens express their newfound tension and confusion.

The teenage years are also a time when children become more socially sensitive. At the age that most teenagers are concerned with acne, popularity, grades, and dates, teens with autism may become painfully aware that they are different from their peers. They may notice that they lack friends. And unlike their schoolmates, they aren't dating or planning for a career. For some, the sadness that comes with such realization motivates them to learn new behaviors and acquire better social skills.

Adults with an autism spectrum disorder

Some adults with ASD, especially those with high-functioning autism or with Asperger syndrome, are able to work successfully in mainstream jobs. Nevertheless, communication and social problems often cause difficulties in many areas of life. They will continue to need encouragement and moral support in their struggle for an independent life.

Many others with ASD are capable of employment in sheltered workshops under the supervision of managers trained in working with persons with disabilities. A nurturing environment at home, at school, and later in job training and at work, helps persons with ASD continue to learn and to develop throughout their lives.

The public schools’ responsibility for providing services ends when the person with ASD reaches the age of 22. The family is then faced with the challenge of finding living arrangements and employment to match the particular needs of their adult child, as well as the programs and facilities that can provide support services to achieve these goals. Long before a child finishes school, parents will want to search for the best programs and facilities for their young adult. Asking other parents of children with ASD about the services available in the community can be helpful. If the community has little to offer, parents often need to serve as an advocate for their child and work toward the goal of improved employment services. Parents often find that it is important to research the available resources as much as possible about the help a child is eligible to receive as an adult.

Living arrangements for the adult with an autism spectrum disorder

  • Independent living: Some adults with ASD are able to live entirely on their own. Others can live semi-independently in their own home or apartment if they have assistance with solving major problems, such as personal finances or dealing with the government agencies that provide services to persons with disabilities. This assistance can be provided by family, a professional agency, or another type of provider.
  • Living at home: Government funds are available for families that choose to have their adult child with ASD live at home. These programs include Supplemental Security Income (SSI), Social Security Disability Insurance (SSDI), Medicaid waivers, and others. Information about these programs is available from the Social Security Administration (SSA). An appointment with a local SSA office is a good first step to take in understanding the programs for which the young adult is eligible.
  • Foster homes and skill-development homes: Some families open their homes to provide long-term care to unrelated adults with disabilities. If the home teaches self-care and housekeeping skills and arranges leisure activities, it is called a skill-development home.
  • Supervised group living: Persons with disabilities frequently live in group homes or apartments staffed by professionals who help the individuals with basic needs. These often include meal preparation, housekeeping, and personal care needs. Higher functioning persons may be able to live in a home or apartment where staff only visit a few times a week. These persons generally prepare their own meals, go to work, and conduct other daily activities on their own.
  • Institutions: Although the trend in recent decades has been to avoid placing persons with disabilities into long-term-care institutions, this alternative is still available for persons with ASD who need intensive, constant supervision. Unlike many institutions years ago, today’s facilities view residents as individuals with human needs and offer opportunities for recreation and simple but meaningful work.

Related Problems

  • Sensory problems: In ASD, the brain seems unable to balance the senses appropriately. Some ASD children are oblivious to extreme cold or pain. An ASD child may fall and break an arm, yet never cry. Another may bash his head against a wall and not wince, but a light touch may make the child scream with alarm.
  • Mental retardation: Many children with ASD have some degree of mental impairment. When tested, some areas of ability may be normal, while others may be especially weak. For example, a child with ASD may do well on the parts of the test that measure visual skills but earn low scores on the language subtests.
  • Seizures: One in four children with autism develops seizures, often starting either in early childhood or adolescence. [22] Seizures, caused by abnormal electrical activity in the brain, can produce a temporary loss of consciousness (a “blackout”), a body convulsion, unusual movements, or staring spells. Sometimes a contributing factor is a lack of sleep or a high fever. An EEG (electroencephalogram—recording of the electric currents developed in the brain by means of electrodes applied to the scalp) can help confirm the seizure's presence. In most cases, seizures can be controlled by a number of medicines called anticonvulsants. The dosage of the medication is adjusted carefully so that the least possible amount of medication will be used to be effective.
  • Fragile X syndrome: This disorder is the most common inherited form of mental retardation. It was so named because one part of the X chromosome has a defective piece that appears pinched and fragile when under a microscope. Fragile X syndrome affects about two to five percent of people with autism [23]
  • Tuberous Sclerosis: Tuberous sclerosis is a rare genetic disorder that causes benign tumors to grow in the brain as well as in other vital organs. It has a consistently strong association with autism. One to 4 percent of people with autism also have tuberous sclerosis. [24]

Clinical Trials

A list of open clinical trials is available: autism spectrum disorders trials.

Research

Research into the causes, the diagnosis, and the treatment of autism spectrum disorders has advanced. With new well-researched standardized diagnostic tools, ASD can be diagnosed at an early age. And with early diagnosis, the treatments found to be beneficial in recent years can be used to help the child with ASD develop to his or her greatest potential.

  • Postmortem and MRI studies have shown that many major brain structures are implicated in autism. This includes the cerebellum, cerebral cortex, limbic system, corpus callosum, basal ganglia, and brain stem.[25] Other research is focusing on the role of neurotransmitters such as serotonin, dopamine, and epinephrine.
  • Research into the causes of autism spectrum disorders is being fueled by other recent developments. Evidence points to genetic factors playing a prominent role in the causes for ASD. Twin and family studies have suggested an underlying genetic vulnerability to ASD. [26]
  • The Autism Tissue Program studies the postmortem brain with imaging methods in order to better understand why some brains are large, how the limbic system develops, and how the brain changes as it ages. Tissue samples can be stained and will show which neurotransmitters are being made in the cells and how they are transported and released to other cells. By focusing on specific brain regions and neurotransmitters, it will become easier to identify susceptibility genes.
  • Recent neuroimaging studies have shown that a contributing cause for autism may be abnormal brain development beginning in the infant’s first months. This growth dysregulation hypothesis holds that the anatomical abnormalities seen in autism are caused by genetic defects in brain growth factors. It is possible that sudden, rapid head growth in an infant may be an early warning signal that will lead to early diagnosis and effective biological intervention or possible prevention of autism. [27]
  • Placebo-controlled studies of the newer atypical antipsychotics are being conducted on children with autism. The first such study, conducted by the NIMH-supported Research Units on Pediatric Psychopharmacology (RUPP) Autism Network, was on risperidone (Risperdal).[28] Results of the 8-week study were reported in 2002 and showed that risperidone was effective and well tolerated for the treatment of severe behavioral problems in children with autism. The most common side effects were increased appetite, weight gain and sedation. Further long-term studies are needed to determine any long-term side effects. Other atypical antipsychotics that have been studied recently with encouraging results are olanzapine (Zyprexa) and ziprasidone (Geodon).

Prevalence

Data from an earlier report of the CDC’s Atlanta-based program found the rate of autism spectrum disorder was 3.4 per 1,000 for children 3 to 10 years of age. Summarizing this and several other major studies on autism prevalence, CDC estimates that 2–6 per 1,000 (from 1 in 500 to 1 in 150) children have an ASD. The risk is 3-4 times higher in males than females. Compared to the prevalence of other childhood conditions, this rate is lower than the rate of mental retardation (9.7 per 1,000 children), but higher than the rates for cerebral palsy (2.8 per 1,000 children), hearing loss (1.1 per 1,000 children), and vision impairment (0.9 per 1,000 children) [1] The CDC notes that these studies do not provide a national estimate.

In a recent study of a U.S. metropolitan area, 3.4 of every 1,000 children aged 3-10 years old were estimated to have autism. [29] This wide prevalence range points to a need for earlier and more accurate screening for the symptoms of ASD. The earlier the disorder is diagnosed, the sooner the child can be helped through treatment interventions. Pediatricians, family physicians, daycare providers, teachers, and parents may initially dismiss signs of ASD, optimistically thinking the child is just a little slow and will “catch up.” Although early intervention has a dramatic impact on reducing symptoms and increasing a child's ability to grow and learn new skills, it is estimated that only 50 percent of children are diagnosed before kindergarten.

History

In 1943 Dr. Leo Kanner (1894-1981) of the Johns Hopkins Hospital studied a group of 11 children and introduced the label early infantile autism into the English language. Dr. Kanner published the paper, “Autistic Disturbances of Affective Contact” in the Journal Nervous Child.

At the same time a German scientist, Dr. Hans Asperger, described a milder form of the disorder that became known as Asperger syndrome. The children that Dr. Asperger studied had a similar disorder to the children in Dr. Kanner's study without the language delays. The new syndrome was named for Dr. Asperger.

Controversy

Vaccines

In the past few years, there has been public interest in a theory that suggested a link between the use of thimerosal, a mercury-based preservative used in the measles-mumps-rubella (MMR) vaccine, and autism. Although mercury is no longer found in childhood vaccines in the United States, some parents still have concerns about vaccinations. Many well-done, large-scale studies have now been done that have failed to show a link between thimerosal and autism. A panel from the Institute of Medicine is now examining these studies, including a large Danish study that concluded that there was no causal relationship between childhood vaccination using thimerosal-containing vaccines and the development of an autism spectrum disorder [30]

Heavy metals and chelation

Chelation, the process of administering chemical chelating agents that bind to metals in the body and allow the resulting complex to be eliminated though the liver or kidneys, has become a controversial treatment for autism spectrum disorders. The theory is that chelation will remove the heavy metals that result from environmental exposure or possibly from vaccines. Studies are ongoing, including the following:

  • A U.S. study looking at exposure to mercury, lead, and other heavy metals showed only one elevated (mercury) level which was reduced into the normal range when fish was removed from the child's diet. [31]
  • The National Institutes of Health is currently recruiting participants for a study involving mercury chelation to treat autism. [32]

Notable Experts

The five NIH institutes of the IACC have established the Studies to Advance Autism Research and Treatment (STAART) Network, composed of eight network centers. They will conduct research in the fields of developmental neurobiology, genetics, and psychopharmacology. Each center is pursuing its own particular mix of studies, but there also will be multi-site clinical trials within the STAART network.

The STAART centers are located at the following sites:

  • University of North Carolina, Chapel Hill
  • Yale University, Connecticut
  • University of Washington, Seattle
  • University of California, Los Angeles
  • Mount Sinai Medical School, New York
  • Kennedy Krieger Institute, Maryland
  • Boston University, Massachusetts
  • University of Rochester, New York

A data coordination center will analyze the data generated by both the STAART network and the Collaborative Programs of Excellence in Autism (CPEA). This latter program, funded by the NICHD and the NIDCD Network on the Neurobiology and Genetics of Autism, consists of 10 sites. The CPEA is at present studying the world’s largest group of well-diagnosed individuals with autism characterized by genetic and developmental profiles.

The CPEA centers are located at:

  • Boston University, Massachusetts
  • University of California, Davis
  • University of California, Irvine
  • University of California, Los Angeles
  • Yale University, Connecticut
  • University of Washington, Seattle
  • University of Rochester, New York
  • University of Texas, Houston
  • University of Pittsburgh, Pennsylvania
  • University of Utah, Salt Lake City

Public Health

Key legislation

The Children’s Health Act of 2000 was responsible for the creation of the Interagency Autism Coordinating Committee (IACC), a committee that includes the directors of five NIH institutes—the National Institute of Mental Health, the National Institute of Neurological Disorders and Stroke, the National Institute on Deafness and Other Communication Disorders (NIDCD), the National Institute of Child Health and Human Development (NICHD), and the National Institute of Environmental Health Sciences (NIEHS)—as well as representatives from the Health Resource Services Administration, the National Center on Birth Defects and Developmental Disabilities (a part of the Centers for Disease Control), the Agency for Toxic Substances and Disease Registry, the Substance Abuse and Mental Health Services Administration, the Administration on Developmental Disabilities, the Centers for Medicare and Medicaid Services, the U.S. Food and Drug Administration, and the U.S. Department of Education. The Committee, instructed by the Congress to develop a 10-year agenda for autism research, introduced the plan, dubbed a“matri” or a“roadmap” at the first Autism Summit Conference in November 2003. The roadmap indicates priorities for research for years 1 to 3, years 4 to 6, and years 7 to 10.

Related Videos

Author David Shenk talks about the astonishing skills displayed by autistic savants and the plasticity of the ordinary human mind, in this video from BigThink:

Video at Bigthink

Sam Wang (Neuroscientist, Princeton University) explores the state of autism prevention and therapy in this BigThink video "The Autistic Brain": Video at Bigthink


References

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External Links

Autism Society of America

Autism Research Institute

International Rhett Syndrome Foundation

Online Asperger Syndrome Information & Support

Interdisciplinary Council on Developmental and Learning Disorders

DIR/Floortime Model

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